A Free Syrian Army fighter aims an anti-aircraft gun as he stands on the back of a truck in Deir al-Zor September 4, 2013. Picture taken September 4, 2013. REUTERS/Khalil Ashawi (SYRIA - Tags: POLITICS CIVIL UNREST CONFLICT) - RTX137WO

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REUTERS

The war in Syria is not the first conflict to generate calls for outside intervention.